GT Performance Mods 2005+ Mustang GT Performance and Technical Information

Rear Suspension

Old Sep 19, 2021 | 02:00 PM
  #1  
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Rear Suspension

So I was wondering if someone could help me with perhaps the best suspension setup for my needs. I have a 2006 GT and I will be upgrading the engine from 300 to 400hp this winter and the other project I have going is needing to update the suspension. Now this will be a daily driver. I will be keeping the original ride height as well. Just wanted to enjoy a few more ponys going through it. So I'm not looking to race it or be super reckless. Outside of maybe a few of those hard pulls on a country road or highway lol.

So one of the things I was kind of going for was increasing ride comfort. I know, it's a mustang, but still, if done properly and safely, why not right? So I had a few ideas about the setup and wanted some opinions.
My ultimate goal is that balance of soft but safe.

So my thoughts were the combination of monotube and a variable spring or perhaps a twin tube and a constant rate spring. Or can I go softer like a twin tube and a variable rate spring and be safe?

The brands I was aiming towards were KYB for monotube or twin gas. Moog for constant rate and ACDelco for variable rate. (really what's available on rock auto) since I am aiming for original ride height.

Any advice would be greatly appreciated.

Thanks!
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Old Sep 20, 2021 | 06:13 AM
  #2  
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The suspension doesn't really "need" any changes to handle the increased power, except maybe the rear lower control arms to prevent wheel hop. If you have the original OEM rear lower control arms, replace them with aftermarket units that are beefier and have harder bushings (that should stop the wheel hop).

You could replace the struts and shocks with something a little "better" such as Bilsteins for a well controlled but not overly harsh ride, and keep the stock springs. Most aftermarket springs are designed for lowering and it does not sound like that's what you want.


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Old Sep 21, 2021 | 02:18 PM
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Aftermarket rear LCA's alone won't prevent wheel hop. Upgrading from stock strut/shocks to aftermarket brands such as Koni and Bilstein are also just as important as well, as they provide much improved control/stability over stock.
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Old Sep 21, 2021 | 07:00 PM
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If you're lowered, yes, shocks and struts. If you're not... maybe not?

I had put on the square tube BMR poly LCAs and didn't swap out shocks, and wheel hop was gone. However, I'd also lowered the car 1" and also put on the adjustable poly BMR panhard bar to ensure left/right centering, so there was that. I had also NOT put in the upper link. That was later, much much later (and what a pain in the behind parts, but I did it.)

I'm thinkin' that stock should try the LCAs and see what they think, then if they want to do shocks/struts, go for it.

/Still dunno why Ford has/had four different part numbers for shocks/struts for the V6/V8 and Coupe/Convertible setups. Seems silly, just dampen the motion, right? Nope, Ford had them tuned for each weight to dampen to a particular height range. You lower the car an inch and they go stupid. Source: me. And then investigation as to why. Just... why.
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Old Sep 22, 2021 | 05:43 AM
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Originally Posted by houtex
. . . I had put on the square tube BMR poly LCAs and didn't swap out shocks, and wheel hop was gone. However, I'd also lowered the car 1". . .
yeah I have read, but not tested myself, that the LCA's are key to controlling wheel-hop; because wheel-hop happens when the control arms flex and unflex rapidly over and over under power . . . but the lowering springs might have helped too, because they are generally stiffer and would help stop the wheels from moving up in the "hop" . . . if I was trying to keep the time and money to a minimum, I'd try the LCA's first
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Old Sep 22, 2021 | 04:17 PM
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Originally Posted by houtex
If you're lowered, yes, shocks and struts. If you're not... maybe not?

I had put on the square tube BMR poly LCAs and didn't swap out shocks, and wheel hop was gone. However, I'd also lowered the car 1" and also put on the adjustable poly BMR panhard bar to ensure left/right centering, so there was that. I had also NOT put in the upper link. That was later, much much later (and what a pain in the behind parts, but I did it.)

I'm thinkin' that stock should try the LCAs and see what they think, then if they want to do shocks/struts, go for it.

/Still dunno why Ford has/had four different part numbers for shocks/struts for the V6/V8 and Coupe/Convertible setups. Seems silly, just dampen the motion, right? Nope, Ford had them tuned for each weight to dampen to a particular height range. You lower the car an inch and they go stupid. Source: me. And then investigation as to why. Just... why.
At first, I ran my car with just the Eibach Pro Kit lowering springs paired with the stock struts/shocks, but eventually upgraded to Koni Yellow adjustable struts/shocks due to the travel distance/valve issues caused by running OEM length dampers with lowering springs.

Although the Koni Yellows are compatible for both stock and lowering spring applications, their design is valved more towards lowering spring applications, where as the stock dampers are designed and valved specifically for OEM spring applications.
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Old Sep 22, 2021 | 08:38 PM
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Thanks everyone. Yeah for me, the suspension is simply old and tired. I will definitely swap out the rear lower control arms like everyone here has suggested. I guess for me, since I live by a bunch of northern farm roads, they aren't the most comfortable to drive on. My concern with going with the performance end for the shocks, springs, and struts would be ride firmness on roads that are going to work the suspension a bit harder. I was looking to see if there was a way to get the best of both worlds out of it. From what I've been able to find, Pedders seems to lower it less than any of the lowering performance suspensions by getting it at exactly 1" vs 1.3 inches for the more common lowering height. How do they compare to the bilsteins? (Price is also more friendly than the bilsteins lol)

Also, on a side note. There was a lot of rattle sound coming from the passenger side front wheel well, I figured all the noise was because my ball joint was worn. So I swapped out the control arms for new ones. The car has new sway bar links, sway bar bushings, as well as inner and out tie rods, and I'm still getting a clunk sound from that same wheel well... I've read that the OEM sway bar can be a culprit for this. If this is the case, I've read that some people have eliminated the sway bar all together and installed the shock tower brace to make up for it and it solved the problem. Others have simply replaced the sway bar with an aftermarket to get rid of the noise. Which method would you guys recommend? Is the shock tower brace truly enough by itself, or should I go with a larger diameter sway bar?

thanks!
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Old Sep 23, 2021 | 05:30 AM
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rattle sound is usually the sway bar end links -- since you already replaced them, make sure they are good and tight

clunking from the sway bar could be bushings; there are some spots where you can have metal-to-metal contact around the bushings, if you take a good look at them from under the car you can probably see what I am talking about (someday I'll take and post some pictures of this, common problem) . . . some also say that if you shim the "back" of the bushing, it helps prevent that contact, again if you look at it, that might make sense

shock tower brace is completely different from sway bar and would in no way make up for removing the sway bar, not sure where they got that idea
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Old Sep 23, 2021 | 04:30 PM
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Thanks, yeah I didn't understand how it was supposed to make up for the sway bar either. I didn't know if I was just missing something. And will do. I'll double check everything over.

Thanks again
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Old Sep 25, 2021 | 03:17 PM
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Originally Posted by Bert
rattle sound is usually the sway bar end links -- since you already replaced them, make sure they are good and tight

clunking from the sway bar could be bushings; there are some spots where you can have metal-to-metal contact around the bushings, if you take a good look at them from under the car you can probably see what I am talking about (someday I'll take and post some pictures of this, common problem) . . . some also say that if you shim the "back" of the bushing, it helps prevent that contact, again if you look at it, that might make sense

shock tower brace is completely different from sway bar and would in no way make up for removing the sway bar, not sure where they got that idea
"What He Said"

Originally Posted by TryingToFixHer
Thanks, yeah I didn't understand how it was supposed to make up for the sway bar either. I didn't know if I was just missing something. And will do. I'll double check everything over.

Thanks again
Just as Bert said, strut tower braces aren't related to the lower front suspension nor can make up for the sway bar. More than likely, it's either your sway bar bushings, end link bushings or both causing your clunking noises
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Old Oct 2, 2021 | 02:23 PM
  #11  
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It sounds as though the OP has gotten rid of the rattles by replacing the sway bar bushings and end links. He's now left with a clunk emanating from the wheel well. This might be worn bearings in the stock upper strut mount which is notorious for failing and causing a "clunk" over speed bumps and rough roads. Easy test, open the hood and have a friend raise and lower the car while you place your hand on top of the strut tower. If the bearings are the issue you should be able to feel the clunk. Just a thought.
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Old Oct 23, 2021 | 01:28 PM
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Originally Posted by houtex
If you're lowered, yes, shocks and struts. If you're not... maybe not?

I had put on the square tube BMR poly LCAs and didn't swap out shocks, and wheel hop was gone. However, I'd also lowered the car 1" and also put on the adjustable poly BMR panhard bar to ensure left/right centering, so there was that. I had also NOT put in the upper link. That was later, much much later (and what a pain in the behind parts, but I did it.)

I'm thinkin' that stock should try the LCAs and see what they think, then if they want to do shocks/struts, go for it.

/Still dunno why Ford has/had four different part numbers for shocks/struts for the V6/V8 and Coupe/Convertible setups. Seems silly, just dampen the motion, right? Nope, Ford had them tuned for each weight to dampen to a particular height range. You lower the car an inch and they go stupid. Source: me. And then investigation as to why. Just... why.
When lowered under 2 inches, replacing the stock upper link is not required nor necessary.. My rear suspension is lowered by 1.5" with the stock upper link still in place. No issues with the pinion angle being out of alignment at all.. Anyhow, for what it's worth, just my $.02 lol.
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Old Oct 24, 2021 | 10:24 AM
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I thought as you did, however... The upper link stock is the same rubber that winds up going bad on the LCAs and flexes about on top of it all. Mine got shredded pretty good after a bit. I had to replace it, and so I went with the BMR upper to match the rest of it, and it's a great piece.

The reality is you *can* go without replacing the upper, as it won't much care regarding many things, but you will eventually (and perhaps sooner on a lowered setup ) wind up doing it anyway, just puttin' it off. So why wait, you're under there anyway, right? Right.

And all that with a 1" lower P Spring kit, mind. Definitely under that 2" idea.

So there ya go. Thems my thoughts after experiences.
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Old Oct 24, 2021 | 03:31 PM
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Totally forgot and agree about the rubber eventually wearing out on the stock upper link along with the stock LCA's.. So just as you brought up, they're all eventually going to wind up needing replaced anyhow..
For all I know, the upper link bushing may already be worn out and not even know it yet, despite the LCA bushings appearing to still be in good condition

I also forgot to ask, is your BMR upper link adjustable or non-adjustable?

Last edited by m05fastbackGT; Oct 24, 2021 at 03:53 PM. Reason: Forgot to ask a question
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Old Oct 25, 2021 | 08:26 AM
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Nosir, only adjustable things for the suspension is the tie rods up front as normal and the panhard bar in the back because OCD about L-R alignment.
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Old Oct 25, 2021 | 02:13 PM
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Same here for the adjustable panhard bar in the back.. I have the BMR adjustable panhard bar for the very same reason. Meanwhile, thanks for getting back to me regarding your BMR upper link
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